JPS60129764A - Image forming method - Google Patents

Abstract

PURPOSE:To prevent the disturbance of an image or the mixing of colors by repeating the formation of latent images and development using a developer consisting of plural components by plural times and setting up the amplitude and frequency of an AC component of a development of a developing bias and a gap between an image carrier and a developer carrier to specific values. CONSTITUTION:A photosensitive drum 9 uniformly charged electrostatically by a scorotron charger 50 is exposed by light sent through a rotary polygon mirror 51 and an image forming lens 52 and its electrostatic latent image is formed. The electrostatic latent image is developed by the 1st developing device 11A, and the formed toner image is charged by the charger 50 again without being transferred to the recording paper, exposed and developed by the 2nd developing device 11B. After repeating the development up to the 4th developing 11D, the developed image is transferred to recording paper by a transfer unit 54. When the amplitude of the AC component of the developing bias of the devices 11A-11D is VAC(V), its frequency is f(Hz) and the gap between the drum 9 and the developer carrier is d(mm.), these values are set up so as to satisfy the relation of the formulas ( I ), (II), so that an image formation preventing the image disturbance or color mixing can be attained.

Description

[Detailed description of the invention]

1. Industrial application field, Ming is the process of forming a latent image on the image carrier,
The present invention relates to an image forming method in which the step of developing the latent image using a developer comprising a plurality of components is repeated multiple times to form an image on the carrier. 2. Prior Art A typical example of representing an electrostatic latent image as a multicolor image is related to a color image using an electrophotographic method. In this conventional method, the colors are separated by passing the original document through an optical filter, and the separated light is used (without repeating the steps of exposure, development, and transfer; that is, by repeating the process). There is also a so-called two-color development method in which an electrostatic latent image with 'Jr8 polarity is formed on the same photoreceptor (image carrier) and developed with black and red colored particles.Formation of these multicolor images This method is desirable because it can add color information compared to the information obtained from black and white images, but it has the following problems: (11 Development of each color is completed It is necessary to make a transfer deviation on the transfer body each time, which increases the size of the machine and increases the time required for image formation. (2) It is necessary to maintain the positional deviation If due to the repetitive movement 1'1. Therefore, attempts are being made to downsize the machine by superimposing and developing multiple toner images on the same photoreceptor so that the transfer process only needs to be done once. 8: The agent is a two-component developer composed of 1 to 1 and a carrier;
There is a one-component developer consisting of particles of 1 to 13". Two-component developers require the management of particles of 1 toner appearing in the carrier, but :Electric;1.
It has the advantage of being easy to control. Ma)ko,'I
In a two-component developer consisting of a magnetic carrier and a non-adhesive toner, it is not necessary to contain a single color magnetic substance in each particle, so colors are produced without color turbidity due to the magnetic substance. 1.S- can be used, and i:Q, Y bright color images can be formed. In overlapping development as described above, it is sufficient to repeat the development several times on the photoreceptor on which the 1st image has already been formed, but when developing in the latter stage, This may disturb the toner image formed on the photoconductor, or the 1-toner that has already been deposited on the photoreceptor may return to the developing sleeve, which is the developer conveying member, and this may cause a different color to be developed from the IJ! developer in the previous stage. There is a problem that the toner enters the developing device in the latter stage where the toner is stored, causing color mixing. A means for superimposing an alternating current component on the developing bias without making contact with one row of developer in developing sleeve 7, which is a developer conveying member for developing this electrostatic latent image, is disclosed in, for example, Japanese Patent Laid-Open No. 56-1444.
However, depending on the developing conditions, sufficient image density may not be achieved, and image disturbance and color mixture may not be eliminated. 3. Purpose of the invention The present invention was made in consideration of the above matters, and
It is an object of the present invention to provide an image forming method that uses a developer composed of a plurality of components, has a desired density, and performs recording without image disturbance or color mixture. 4. Structure of the Invention According to the present invention, the process of forming a latent image on an image bearing member and the process of developing the latent image using a developer made of a plurality of components are performed multiple times. In the image forming force method of repeatedly forming an image on the image carrier, in each developing step,
When the amplitude of the alternating current component of the developing bias is ■Ac, (■), the frequency is (Ilz), and the gap between the image ↑ll and the developer conveying body to which the developer is pasted is d (mm), This invention relates to an image forming method characterized by satisfying 0.2≦VAC/ds((v^(,/d) 1500)/s≦1.0. We researched a method of developing and forming an image by multiplying the AC component by 11 times, and found that depending on the development conditions such as AC bias and frequency, it is possible to develop a method that does not cause image disturbance or color mixture. It has been discovered that there is a region in which high-quality images can be obtained.The present invention proposes a novel developing method based on such a discovery. The embodiment shown in the drawings will be explained in detail.First, the process by which the present inventors came to make this invention will be explained. The method of repeating the step of forming an image and the step of developing it and sequentially assembling the toner images is such that during development, the toner image formed on the image carrier in the previous stage can be developed to an appropriate density without disturbing the toner image formed on the image carrier. It is necessary to perform overlapping.Here, overlapping is not to form one image multiple times in the same part of the development area of the image carrier, but to form an image in different parts of the image area. This also refers to the case where a toner image is formed multiple times.As a result of inspection δ・j, if this condition is not met, the image (gap between the storage body and the developer conveyance body d (mm
) (hereinafter sometimes simply referred to as gap d), development high-
Voltage \/Ac and frequency f (+1
It has become clear that even if the value of 7) is determined independently, it is not possible to correct the blurred image, and that these parameters are closely related to each other. Therefore, while changing the parameters such as the voltage and frequency of the AC component of the developing bias,
When an experiment was conducted using the developing device 11 as shown in the figure,
The results shown in FIGS. 2 and 3 were obtained. Note that a toner image is previously formed on the photosensitive drum 9, which is the image carrier 1. In this developing device 11, a sleeve 42 and a magnetic roll 43, which is a developer conveying member ζ, rotate to generally transport the developer on the circumferential surface of the sleeve 42 in the direction of arrow B, thereby developing the developer. It is supplied to area E. Note that the developer is a two-component developer consisting of a magnetic carrier and a non-magnetic carrier, and the carrier has an average particle size of 3.
0μm, magnetization 50emu/g, resistivity 10ΩC1
It is a spherical carrier with 4L1 fat corner ink of n or more, and the resistivity is O, after putting the particles into a container with a tlJi area of 50 cJ and tapping, a charge of 1 kg/cut on the packed particles. Multiply by

[It is. The toner was mixed with thermoplastic resin 9QwL%, pigment (carbon black) (added a charge control agent to 11wt), and kneaded A.
'5) The developer used was crushed and had an average particle size of 1 (l p m).
Each time 2 rotates in the direction of arrow B, it is transported in the direction of arrow B. The developer is removed from the spike control plate 1 during transportation.
40 regulates its thickness. A stirring screen L-41 is provided in the developer reservoir 47 to sufficiently stir the developer reservoir, and when the developer reservoir in the developer reservoir 47 is consumed, the toner supply roller 39 rotates, developer is replenished from the toner hopper 38. A DC power supply 45 is installed between the sleeve 42 and the photosensitive drum 9 to perform reversal development without applying a developing bias, and also to direct the developer to the developing area E.
It is connected in series with an AC power source 46 or a DC power source 45 so that a sufficient amount of developer is supplied to the photoluminescent ram 9 during vibration. R is (λ: Mamoru) 1! , is anti. FIG. 2 shows the gap between the photosensitive drum 9 and the sleeve 42.
! ; i d is 1.0 mm, developer layer thickness is 0.5 mm
, the amplitude of the AC component and the exposed part of the photoreceptor tram discharge (potential is OV) when the charging potential of the photoreceptor is set to 600V, the DC component of the developing bias is set to 500■, and the frequency of the AC component is set to 1z. It shows the relationship between the image density and the toner image formed. The amplitude E Ar of the alternating current electric field strength is the development/'
(It is the value obtained by dividing the amplitude VA6 of the AC voltage of IAS by the gap d. Curves Δ, B, and C, not shown in FIG.
These are the results when using a material whose charge was controlled to 1c/g. For both of the three curves A-B and C, the effect of the alternating current component appears when the amplitude of the alternating component of the electric field is 200 V/mm or more, and when the amplitude is more than 2500 V/mm, the photoreceptor becomes 1 rad. It was observed that the pre-formed toner image was partially destroyed. Figure 3 shows the frequency of the AC component of the developing bias at 2.5K.
The graph shows the change in image centrality when alternating current electric field strength BAc is changed under the same conditions as in the experiment shown in FIG. 2, with lIz. According to this experimental example, when the amplitude E80 of the alternating current electric field strength exceeds 500 V/mrn, the image density increases, and although not shown in the figure, when it exceeds 4 KV/mm, the image density is The toner (part of the elephant's skin was broken by one force).As can be seen from the results in Figures 2 and 3, the image density changes greatly after a certain amplitude; As can be seen from curves A, B, and C, fi does not depend much on the average charge amount of the toner.The reason is thought to be as follows.In other words, in a two-component developer, the toner and the carrier The amount of charge on the toner is expected to be distributed over a wide range, and it is thought that toner with a large charge ■7 will be developed preferentially. Even if the average charge amount is controlled by agent 11, these large ;!
■The proportion of l-ners with electric charge does not change significantly,
As a result, although some changes in development characteristics were observed, they were not observed to be significant. Now, when experiments similar to those shown in FIGS. 2 and 3 were conducted while changing the conditions, the relationship between the amplitude EAc of the alternating current electric field strength and the frequency 1,000 could be sorted out, and the results shown in FIG. 4 were obtained. In FIG. 4, the areas marked with ■ are areas where uneven development is likely to occur, the areas marked with black are areas where the effect of the alternating current component does not appear, and the areas marked with ■ are likely where toner backflow occurs. That is, areas where color mixing is likely to occur, (1) and (2) are areas where the effect of the alternating current component appears and color mixing does not occur, and (2) is a particularly preferred area. This result shows that the amplitude of the AC electric field strength and its This shows that there is an appropriate range for each frequency.
The cause is considered to be due to the reasons described below. The image density increases as the amplitude of the AC field strength EA(,
Region 1 in the φ direction (for example, for the concentration curve in Figure 2, the intersection is A, the amplitude EAC of the electric field strength is 0.2 to 1.2
For the area of KV/mm, the development bias intersection b
The component makes it easier to exceed the darkness value at which the toner flies from the sleeve, and even a small -i3 charge of 1-toner is deposited on the photoreceptor drum 9 and subjected to development. (jL°ζ, as the amplitude of the AC electric field strength increases, the image density increases. On the other hand, the area where the image 61 degrees is saturated with respect to the amplitude 1 crystal EAo of the AC electric field strength, the curve of the 21st Soj) In the region where the amplitude EAc of the AC field strength is 1.2 KV/mm or more, this phenomenon can be explained as follows.In this region, as the amplitude of the AC field strength increases, If the toner is strongly vibrated, the clusters formed by toner agglomeration will be easily broken, and 1 with a large electric charge will be generated.
- Toner particles are selectively deposited on the photoreceptor drum 9, and toner particles with small charges are difficult to develop. Furthermore, even if the toner with a small electric charge is attached to the photoreceptor drum 9, its mirror image force is weak, so that it is likely to return to the sleeve 42 by the alternating current bias. Furthermore, if the amplitude of the electric field strength of the alternating current component is too large, charges on the surface of the photoreceptor drum 9 will leak, making it more likely that the toner will be difficult to develop. In reality, it is considered that these factors overlap to keep the image density constant with respect to the itt addition of the alternating current component. Furthermore, if the AC flil is increased and the amplitude is increased to 2.5 ν/mm or more under the conditions obtained for the curve in FIG. 2, as described above, the It was found that the toner image that had been placed was destroyed, and that the larger the alternating current component, the greater the degree of destruction. The reason for this is thought to be that the 1-ner adhering to the photoreceptor drum 9 is pulled back to the sleeve 42 by the alternating current component. When toner images are sequentially superimposed on the photoreceptor drum 9 and developed, it is a fatal problem that the toner images that have already been formed are destroyed during subsequent development. Also, as can be seen by comparing the results in Figures 2 and 3, when we experimented by changing the frequency of the AC component, the higher the frequency, the lower the image density. This is due to the fact that the vibration range is narrowed because the vibration cannot follow changes in the calculation, and it becomes difficult to adhere to the photoreceptor drum 9. Based on the above experimental results, the present inventor has determined that in each development step,
The amplitude of the AC component of the developing bias is 0.2 ≦
VAc/d・S(('v, o/d)-1500)/S≦1.0, and if development is performed under the conditions, the toner image already formed on the photoreceptor drum 9 will not be disturbed. It was concluded that subsequent development could be carried out at an appropriate density. In order to obtain sufficient image density and not disturb the toner image formed up to the previous stage, please follow the above steps! Among 1, 0.5≦V^. /d −f ((VAC, / d>-1500) /su ≦1.0. Furthermore, especially among these, 0.5≦
■＾c / d - evening ((VAC/d) -1500) /l ≦0.8, you can obtain clearer multicolor images with no color clouding, and the developing device will remain stable even after multiple operations. ; It is possible to prevent toner of a different color from being mixed into ξ. In addition, in order to prevent uneven development due to the AC component, the frequency of the AC component is set to 200+17. As described above, the rotating magnetic l:J-
When using a magnetic roller, it is more desirable that the frequency of the alternating current component be 50011z or higher to avoid the effects of beats caused by the alternating current component and the rotation of the magnetic roll. The configuration of the present invention is as described above, but in order to sequentially develop subsequent toner images at a constant density on the photoreceptor drum 9 without destroying the toner image formed on the photoreceptor drum 9, As development is repeated, ζ ■ Sequentially use toner with a larger charge ↑d. ■ Gradually reduce the amplitude of the electric field strength of the AC component of the developing bias. ■ Gradually increase the frequency of the AC component of the developing bias. It is even more preferable to use iW and IW in combination with each other individually or by omission. In other words, the more highly charged the toner particles are, the more easily they are affected by the electric field. Therefore, in early development;! 1: If 1.sub. particles with a large amount of charge adhere to the photoreceptor drum 9, the 1.sub. particles may return to the sleeve during subsequent development. Therefore, the above-mentioned point (2) is that 41) 1-toner particles having a small electric charge are used in the initial development to prevent the toner particles from returning to the sleeve during the subsequent development. ■As development is repeated (i.e.,
This method prevents the toner particles already deposited on the photoreceptor drum 9 from returning by gradually reducing the electric field strength (the later the development stage is). A specific method to reduce the electric field strength is to reduce the AC component voltage to M11.
There is a method of increasing the gap (1) between the photoreceptor drum 9 and the sleeve 42 as it is used for later stages of development. This is a method of preventing the return of particles that are already attached to the photoreceptor drum 9 by increasing the frequency.These ■■■ are effective even when used alone. For example,
It is even more effective to use a combination of increasing the l/ner charge and gradually decreasing the alternating current bias as development is repeated. Also, below
By adjusting the DC bias on each of the three sides of I, it is possible to maintain an appropriate image density or color balance. An embodiment will be explained using Figs. 5 and 7. Embodiment 1 Fig. 5 is a schematic diagram of the main parts of a color image forming device, and is uniformly manufactured by Scoroto 1'Jn;lj Denki. The photoreceptor drum 9, which has been charged to 'Vi image is formed. This electrostatic lj↑1 image is developed by the first developing device 11Δ, and a first 1-ner image is formed on the photosensitive drum 9. - The toner image is transferred to the recording paper and is again charged and exposed by the electronic device 50, and then a second toner image is formed by the second developing device 1113. This continues until the fourth No-image is formed. Immediately,) ii electric (not necessarily necessary from the second time) -
・This is a process in which the exposure-one development process is repeated four times without including the transfer process. After the toner image is completely formed on the photo drum 9, the area where the toner image on the photo drum 9 is shaped like 1j:Q is recorded by the pre-transfer exposure 53. !(After 1 trip, this toner image is transferred by the converter 54 onto the recording paper (its warp 11'a is shown by a broken line) fed from the paper feeder; ¥7 (1!l not shown). .The paper is rolled through at least one heated roller.
The image is heated and fixed by the fixing device 57, which is composed of
(during toner image formation, the composite drum 9 removes any excess charge remaining on the surface after being neutralized by the static eliminator 55, which was not in use). The toner is removed by the cleaning device 5 [j] (the toner inside the figurine is removed by 1). This color image forming apparatus repeats the above operation every time the operation button is operated. +'i [In this example, selenium is used as the photoreceptor, and the photoreceptor is
¥4j: 120mm, peripheral speed 12 (1mm/sac
, the charging potential is ['i00 V, the developing device 11A, 11)3. A developing bias of IKII2 is applied, and the gap d between the photosensitive drum 9 and the sleeve of each developing device is 0.8.
It is set to mm. Also, is the developer magnetic 1? [It is a two-component IJJ imager consisting of a carrier and a non-theta-resistant toner. This carrier has an average grain size of ¥30 μm and a magnetization of 5Q6mu.
A resin-coated spherical carrier i' with a resistivity lQ QC+11 or more is used. Toner: thermoplastic resin 9QwL%, ready-to-use 1Qwt% and a little h1
The developing device 11A has a structure in which a charge control agent of 1, 1, . f series, magenta series for 11B,
For IIC, cyan thread is used, and for 1it), foil is used, and the average 411 Denhare is 20 μc / g and the average particle size is 10 μm. A mixture of the carrier and toner described in -1- at a ratio of 3Qwt% and 20wL%, respectively, is used as a developer. Further, in each developing device, the sleeve 42 and the magnetic screw 43 are rotating in opposite directions, and the parallel blades are used to
The i j↓3 system is used, and the developer layer thickness is 0.4 m.
It's become m. As mentioned above, the toner images are sequentially
When a multicolor image is formed by combining them, the toner image already formed on the photoreceptor 1-ram 9-hi may be destroyed during subsequent development, or toner of another color may be mixed into each developing device. A visible image with sufficient density was obtained without any problems. When this superimposed toner image was transferred to recording paper and fixed, a clear recorded image was still obtained. Also, even after recording many sheets of transfer paper, other colors were mixed into each developing device. In addition, by incorporating a magnetic material into the 1-ner of each developing device, it is possible to further prevent image fogging due to the combined force.Example 2 Same as Figure 5. The DC component used in the color image forming apparatus shown in FIG.
, 500 V, 111], 1.0 mm, 550
It is set to V. The iF average in the toner (1:1), the AC bias amplitude, and the frequency are similar to those in Example 1, and are common to each developing device, and each is 20μ.
C/g, IKV, 1 Kllz. This prevents the toner from returning to the photoreceptor drum 9-1, and the density balance of the 1-toner images of each color is maintained by increasing the DC bias to 1jQ. According to this embodiment, even clearer images were obtained, and even after recording a large number of sheets, no other color was mixed into each developing device. Example 3 Same (implemented in the color image forming apparatus shown in FIG. 5).The difference from Example 1 is that the AC component and DC component of the applied developing bias differ depending on the developing device, and in the developing device 11Δ, , the amplitude of the AC component and the DC component are each 1,
5KV, 450v, 1113te is 1.2KV, 500
V, IIc 1. OKV, 520 V, 11D is set to 0.8 KV, 550 ■. 1.Average charge amount of empty toner, AC) 1471 frequency, gap between photoreceptor drum 9 and sleeve is common to each developing device as in Example 1, and is 20 M'C/g, 1 K11z, 0, respectively.
．． It is 8mm. In this Example 1 and 1, the AC component is set to decrease in the order of development to prevent the toner from returning on the θ light body Drano, 9, and by increasing the DC bias sequentially, The density of each color toner image is balanced. This example also produced a clear multicolor image, and even after recording a large number of sheets, no other colors were mixed into each developing device. Example 4. The development is carried out using the color image forming apparatus shown in No. 5121.The developing conditions are that the amplitude of the AC component of the developing bias (r,) is IKV for each developing device, and the frequency and DC component are IKV in IIA. 800IIz and 450 respectively
V. 1113 has 1 to 11z, 500■, IIC has 1.5
K11z, 550V, IH) is 2Kllz, 600
■It is set to tee. In addition, in each developing device, the center of the sleeve rotates and J:iJ
1 (Rho agent is supplied, and the internal magnet is fixed. The height of the head is controlled by a magnetic blade, the gear knob is 0.5+nm, and the developer layer thickness is 0.2
It is mm. The average amount of toner (i), the gap between the photoconductor 1 and the ram 9 and the sleeve is common to each developing device, and each is 20μc4.0
．． 8 mm, and other developing conditions and developer were the same as in Example 1. In this embodiment, the frequency of the AC component is set so that it increases in the order of development, thereby preventing the return of I/ner on the photoreceptor drum 9 and reducing the DC bias to 1 ll.
By doing this, the balance of the density of each color I and color image is maintained. This embodiment also produces a clear multicolor image (JI), and even after recording a large number of sheets, each developing device is No color was mixed in. FIG. 6 is a first-edge chart that does not show changes in the potential on the photoreceptor tram 9 when development is performed by the color image forming apparatus of FIG. P I-1 is an exposed area, and OA is a non-exposed area. When charged by the scorotron charger 50, the photosensitive tram 9 maintains a constant potential, and when image exposure is performed, the area irradiated with light Next, by applying a bias whose DC component is approximately equal to the potential of the unexposed area to the developing device, the positive 4) single-voltage toner in the developing device is mixed and the potential is low. Some particles are deposited on the exposed area, development is performed, and a first visible image is formed.As the positively charged toner adheres, the potential of this area increases slightly (in the figure, DIJ 1)). Next)+? Electric appliances 5
Each time it is re-charged with zero, the potential on the photoreceptor tram 9 is uniformly charged so that it rises to a predetermined potential (indicated by CIJP in the figure). Next, a second image exposure is carried out, and development is carried out in the same manner.
The 1-ner adheres to the exposed areas and a second visible image is formed. By repeating this four times, visible images of four colors are formed on the photosensitive drum 9 by combining and heating. In the Two-L method, charging for the second and subsequent times can be omitted. In addition, if the i-electrification is not omitted, a static elimination step may be performed before charging. Although the three embodiments described below all use the reversal development method, there are also things that can be done using the regular development method, that is, the method of attaching toner to the non-iW light area and forming a toner image. No need to look at it. However, in the case of overlapping development using the regular development method, it is necessary to perform a charging step each time. Embodiment 5 Next, a case in which development is performed using the color image forming apparatus shown in FIG. 7 will be described. The photoconductor tram 9 uses a Cds photoconductor whose surface is covered with an insulating layer, and has a diameter of 12 mm (1 mm) and a circumferential speed of 120 mm.
/sec, insulation layer thickness 20μm, 7B5 light 1M 15
': 30 tt m. First, the surface of the photoreceptor 1 ram 9 is charged to -1000V by the negative charger 58 while the entire surface is exposed to light by a lamp provided in the charger 58. This exposure is performed to facilitate charge injection into the photosensitive layer in the photoreceptor tram 9. Then, it is charged to -100V by a secondary charger 59 having an AC component, thereby reducing the positive charge on the surface of the insulating layer. The photosensitive drum 9 charged to -100V is imagewise exposed by the reflected light from the rotating polygon mirror 51, and the exposed portion has a positive potential, is developed by the first developing device 11A, and is exposed to the first photoreceptor. A visual image is formed. Next, the photoreceptor tram 9 is once again supplied with a current of -10 (IV) by the secondary voltage generator 59, and is subjected to image exposure, and a second visible image is formed from the second developing device 11B4. After this is repeated four times and all the visible images are formed on the photoreceptor drums 9 and 3, the transfer m1 exposure lamp M irradiates the area of the photoreceptor drum where the visible image has been formed, and the transfer 1j, this visible image is placed on the recording paper (its path is shown by a broken line) sent from the feeding device (not shown) by the container 54!I11
: Take a photo. The recorded image i'JL is heated and fixed by a fixing device 57 including at least one heated roller, and then transported outside the machine. After the photoreceptor tram 9 has been transferred, the charge is removed by the static eliminator 55, which was not used during the 1-toner image formation, and the excess toner remaining on the surface is removed. It is removed by the cleaning device 5fi, which was previously released. This color image forming apparatus repeats the above operation every time the operation II+ is operated. The developing conditions for each developing step are that the AC component of the developing bias is 1.5 KV, and the frequency is 2 Kl.
lz, the DC bias was OV, and the gap d between the photosensitive drum 9 and the sleeve of each developing device was 0.5 mm.
is set to . In each developing device, a sleeve and a magnetic roll rotate in the same direction to convey developer 2, and the thickness of the developer layer is regulated to 0.3 mm by a magnetic plate 1'. Each developer had the same structure as in Example 1, except that the charge was controlled to -20 μc/g. When a multicolor image is formed using the above configuration, during the subsequent development stage, the 1st image already formed on the photoreceptor 1 ram 9 may be destroyed, or each developing device may contain images of other colors. FiJ visual image with a high concentration without contamination of
It's q. Embodiment 6 This is carried out using a color image forming apparatus shown in FIG. Example 5! ! -1 because the average charge amount of the developer used and the DC component of the applied developing bias differ depending on the developing device.
/Jc /g, 0 V, IIB is -15μc/
g, 0v, IIC -20pc/g, 20V
, jlD is set to -40μc/g and 50V. The amplitude and frequency of the alternating current bias and the gap between the photosensitive drum 9 and the sleeve are common to each developing device as in Example 5, and are i, 5 KV, 2 KIIz, and 0.5 mm, respectively. In this embodiment, the charge is controlled so that the absolute value of the average charge amount of the developer increases in the order of development, thereby preventing the toner from returning to the photoreceptor drum 9-, and the value of the DC bias is sequentially adjusted. By increasing the size, the density of each color toner image is kept balanced. A clear multicolor image was also obtained in this example, and no other colors were mixed into each developing device 6 even after recording a large number of sheets. administered. The difference from Example 5 is that the average charge amount of the developer used and the amplitude of the alternating current component of the applied developing bias differ depending on the developing device. 1.6KV, 11 in llB
5μc/g, 1.4KV, 110, -20 is common to each developing device as in Example 5, and 2K1 each.
1z, 0 V, 0.5 mm. By controlling the amount and setting the alternating current bias to be as small as λ1n, the photoreceptor drum 91. This prevents toner from returning and at the same time maintains a balance in the density of each color toner image. According to this embodiment, even clearer multicolor images were produced by 1-+1, and even after recording a large number of sheets, no other colors were mixed into each developing device. FIG. 8 shows changes in the potential of the photosensitive drum 9H when development is performed by the color image forming apparatus shown in FIG. - After being positively charged by the secondary charger 58, the secondary charger 5
9, the surface potential of the photosensitive drum 9 becomes approximately 0. Next, as image exposure is performed, the potential of the area irradiated with light increases, and negatively (dielectric) toner is deposited on this area in the developing device. The potential decreases (indicated by Dr+w4- in the figure).Next, the surface potential is uniformly charged again by the secondary charger so that the surface potential becomes approximately 0V, and image exposure and development are repeated. After the visible images of all colors have been repeatedly formed on the photoreceptor drum 9-, each toner image is transferred to recording paper, and the photoreceptor 1-ram 9 is destaticized and cleaned, and the next image is transferred to the recording paper. Proceed to the image forming step. In the above method, it is possible to omit secondary charging from the second time onwards.Also, -order and secondary charging may be performed every time, in which case the In each of the embodiments described above, corona transfer is used as the method of transferring the l/ner image, but other methods may also be used.For example, , Special Public Interest Publication No. 46-4167
By using the adhesive transfer described in Japanese Patent No. 9 and Japanese Patent No. 48-22763, it is possible to perform the transfer without considering the polarity of the toner. Furthermore, a method of directly fixing the image on the photoconductor, such as electrofax, can also be adopted. It is particularly preferable that the two-component developer used in the present invention is composed of a magnetic carrier as a carrier and a non-magnetic toner as a toner. Examples: Polystyrene, styrene acrylic polymer, polyester, polyvinyl butyral, epoxy resin, polyamide resin, polyethylene, ethylene-vinyl acetate co-electric polymer, etc. are often used in combination. (2) Pigment: Colored grain 0-I5wL% Example: Black: Carbon furanok Blue: Copper phthalocyanine, sulbonamide dielectric dye Yellow: Henjin derivative Magenta: Polytangues I-phosphoric acid, Rhodamine B lake-, Carmine 6B, etc. (3) Charge Control agent Q~y8% Example Nibrass: Nigrosine type (electron donating property) Minus: Organic complex (electron accepting property) (4) Fluidizing agent example: Colloidal silica, hydrophobic silica are typical,
Other products include silicone face, metal soap, and nonionic surfactants. (5) Cleaning agent Prevents toner from filming on the photoreceptor. Examples: fatty acid metal salts, oxidized silicon acids with organic groups on the surface,
There are fluorine-based surfactants. (6) The purpose is to improve the surface gloss of filler images and reduce raw material costs. Examples: calcium carbonate, clay, talc, pigments, etc. In addition to these materials, a magnetic material may be included to prevent toner from scattering. As magnetic powder, triiron tetroxide, γ-ferric oxide, chromium dioxide, nickel ferrite, iron alloy powder, etc. with a size of 0.1 to 1 μm have been proposed, but at present, the resistance of the toner changes due to peeling. However, in order to obtain sufficient resistance, it is preferable that the amount of magnetic material be 55 wL% or less. Further, in order to maintain clear colors as a color toner, it is desirable that the amount of magnetic material be 3QwL% or more. Other resins suitable for pressure fixing toner include approximately 20
Adhesive resins such as wax, polyolefins, ethylene-vinyl acetate copolymers, polyurecne, and rubber are selected so that they can be plastically deformed and adhered to paper with a force of about kg/cm. Capsule toners can also be used. Using the above-mentioned materials, the containers 1 to 1 can be made using conventionally known manufacturing methods. In the structure of the present invention, in order to obtain a more preferable image, it is desirable that the average particle size of these toner particles is approximately 50 microns or less in view of the resolution. In this method, there is no theoretical limit to the toner particle size, but from the viewpoint of resolution, toner scattering, and conveyance, it is usually preferably about 1 to 30 microns. In addition, in order to create delicate points or lines or to improve gradation, magnetic carrier particles are particles made of magnetic particles and resin, such as a resin dispersion system of magnetic powder and resin, or resin-coated magnetic particles. More preferably, particles are spherical and have an average particle diameter of preferably 7 to 50 μm, particularly preferably 30 to 5 μm. In addition, the bias voltage causes charges to be injected into the carrier particles, which hinders good image formation, causing the carrier particles to easily adhere to the surface of the image bearing member, and the bias voltage not being applied sufficiently. In order to prevent this, the resistivity of the carrier is 10 Ωcm or more, preferably 10 Ωcff1 or more, and more preferably 10 9 cm.
The above-mentioned insulating materials are preferable, and those having the above-mentioned resistivity and particle size are also preferable. A method for manufacturing such a finely divided carrier is to use a magnetic material and a thermoplastic resin as described for toner, and coat the surface of the magnetic material with the resin, or coat the particles with a resin containing fine magnetic particles dispersed therein. It can be obtained by preparing particles and selecting the particle size using a conventionally known average particle size selection means. It is desirable to make the carrier spherical in order to prevent toner particles from collapsing together or between toner particles and carrier particles. Select spherical particles and apply a resin coating treatment to them. For carriers with magnetic fine particle dispersion, use magnetic fine particles as much as possible, and after forming the dispersed resin particles, perform a spheroidization treatment with hot air or hot water. Alternatively, it can be manufactured by directly forming spherical dispersed resin particles using a spray drying method. Note that the present invention can be further modified based on its technical idea. In the examples, as a developer consisting of multiple components,
Although a two-component developer consisting of toner and carrier has been described, a developer containing a third component may also be used. In the embodiment, only the development of a color image is described, but the present invention can also be applied to developing the same color toner in multiple batches. In this case, a toner image with excellent HIfa properties can be formed on the photoreceptor drum 9. Further, the present invention can be applied to non-impact printers that utilize not only electrophotographic recording methods but also electrostatic recording methods and magnetic recording methods. 6. Effects of the Invention According to the present invention, even if the process of forming a latent image on an image carrier and the process of developing the latent image using a developer consisting of a plurality of components are repeated multiple times, the previous stage does not change. It is possible to form a subsequent image on the image carrier without disturbing the formed image. In other words, the amplitude VAc of the alternating current component of the developing bias, its frequency, and the relationship between the developer carrier and the image carrier Clear images can be produced on the image carrier by setting the gap d so that the mutual relationship does not satisfy 0.2≦VA(/d・min((VAC/d) 1500)/s≦1.0. can be formed.

[Brief explanation of the drawing]

(Figures 1 to 3) (The figures show examples of the present invention. Figure 1 is a cross-sectional view of the developing device and photoreceptor drum, and Figures 2 and 3 are cross-sectional views of the developing device and the photosensitive drum. Figures 2 and 3 show examples of the present invention. Figure 4 is a diagram showing the density characteristics when the electric field strength and frequency are changed, and Figures 5 and 1 are diagrams showing the change in image density when multiple developing devices are used. 6 is a diagram showing changes in the surface potential of the photosensitive drum used in the color image forming apparatus shown in FIG. 5, and FIG. It is a diagram showing changes in the surface potential of the photoreceptor tram used in the color image forming apparatus shown in the figure.The symbols used in the drawings are 9...
...Photosensitive drum 11.11Δ, IIBIIClIID...
・Developing device 14.56...Cleaning device 42...Sleeve 43
・・・・・・・・・・・・・・・Magnetic roll 45...
.......DC bias power supply 46...
・・・・・・・・・・・・AC bias power supply D・・・・
・・・・・・・・・−・Developer d・・・・・・・・・・
...Gap EAC between photoconductor drum and sleeve...
......It is the amplitude of the alternating current electric field strength. Agent Patent Attorney Hiroshi Aisaka (1st name) 4th Ell. 20 JC 30th O123 rkv/me-] I:Ar Figure 5 60 (1 shot) Proceedings Patent Office Kazuo Wakasugi `` 1. Case Indication of 1980! Time Application No. 238296 2, Title of the invention Image forming method 3 Relationship with the Natsuki Shima matter to be amended Patent publication 1ji, 1-i u lr name ('(l I'l・)( +27) Konishiroku Photo Koju Co., Ltd. 4, agent address: Suzuki Building 2, 3-9-17 Shibasaki-cho, Tachikawa-shi, Tokyo (-
Stomach 6, Number of inventions increased by amendment 7, Subject of amendment 8, Contents of amendment (2), [0,2≦■Ac/d-f on page 6, line 6 of the specification
] is corrected to "0.2≦■Ac/(d-f)". (3), p. 8, line 9 IJ) r 30 pll,”
Correct it to ``30 pm (average particle size is weight average particle size, measured with Omniconi Alpha (manufactured by Bausch & Lomb) Toca and Coulter Counter (manufactured by Coulter).'' (4) In the 13th line of page 8, correct [multiply by, load] to "multiply by, so that the carrier particles have a thickness of about 1w, and then calculate load." (5), "0.2≦VAc/d-f" in the first line of page 15
Corrected as [02≦VAc/(d-f)”Lt-j-0(
6), "0.5≦VAc/df" on the 9th line of page 15 was corrected to [0,5≦VAc/(df)] L1t. (7), page 15, line 12, “0.5≦vAc/d−f
” to [0,5≦VAC/ (d-f) JLt-
t. (8), “0.2≦vAc/df” on page 38, line 7
is corrected to ``0.2≦VAC/ (d・f) J.'' - Above, - Claim 1: A process for forming a latent image on an image bearing member, and a developer comprising a plurality of components. In an image forming method in which an image is formed on the image carrier by repeating the step of developing the latent image using a plurality of times, in each developing step, the amplitude of the alternating current component of the developing bias is set to vAC (v). , the frequency is /(Hz), and the gap between the image bearing member and the developer transporting member that transports the developer is d (
-), 0.2≦■Ac/(d-f) ((VAC/d) -1500) / f≦1.0
An image forming method in which the percentage is satisfied. 2. In each developing step, the gap between the image carrier and the developer transporting member is maintained larger than the thickness of the developer layer formed on the developer transporting member. Image forming method 〇3 described in Item 1, Claims and Claims 1 or 2 characterized in that a multicolor image is formed by sequentially using the developer having the smallest absolute value of the average charge amount.
Image forming method 04 described in Section 1, characterized in that the amplitude of the alternating current component of the electric field between the image bearing member and the developer transporting member in each developing step is successively reduced to form a multicolor image. The image forming method described in any one of Items 1 to 3. 5. Claims 1 to 4 of Claims 1 to 4, characterized in that a multicolor image is produced by sequentially increasing the frequency of the alternating current component of the electric field between the image carrier and the developer transporting member in each development process. The image forming method described in any one of the above. (Voluntary) Procedure Niff official book 3rd year of 1982? Day 1, Indication of the case 1982 Patent Application No. 238296 2, Name of the invention Image forming method 3, Relationship with the case to be amended Patent applicant address 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Name name
(127) Roku Konishi Photo Industry Co., Ltd. 4, Agent 6, Number of inventions increased by amendment 7, Claims column of the specification to be amended and Detailed description of the invention column (1), Patent claim Correct the range as shown in the attached sheet. (2), [Used] in the 3rd to 2nd lines from the bottom of the 8th specification. ``Developer D'' was used.The toner was mixed at a ratio of 2Qwt% to 80wt% of the carrier to prepare a developer.The toner is positively charged due to friction with the carrier.Developer D ” I corrected myself. (3), in the first line from the bottom of No. 9, change “formed to” to “
"It is formed by reversal development." (4) On page 12, lines 1 and 2, "areas where color mixing is likely to occur, that is, areas where color mixing is likely to occur" has been corrected to "areas where it is likely to occur." (5), "Color mixing" in the second line of page 12 has been corrected to "toner backflow." (6) On page 14, line 4 of the same article, ``The ner is pulled back to the sleeve 42 by the alternating current component'' has been corrected to ``The ner is pulled back to the sleeve 42 by the alternating current component.'' (7), ``Seregato'' in the 6th line from the bottom of page 16 [
I corrected myself by saying, ``I can't get hired in the first place.'' (8), “No\ias is applied” on page 20, line 1.
First, correct it to ``bias is applied during each development''. (9) In the 7th line from the bottom of No. 20, "In each developing device, the sleeve 42" is changed to "In each developing device, the sleeve 42 is used during development."
2” and correct it. (10), ``While rotating'' in the 6th line from the bottom of page 20 is corrected to ``while rotating'' as j. (11), on page 21, line 7 from the bottom, ``and is applied'' has been corrected to ``applied during base development and development''. (12), on page 22, line 8 from the bottom, "applied" is corrected to "applied during development." (13), "Development no\ias" in the 7th line from the bottom of No. 23 is corrected to "Development no\ias applied during one development." (14), “sleeve” in the second line from the bottom of page 23 is r
cdsJ, I correct it. (16), the first line from page 26 F of the same page is corrected to read, ``Developing bias applied during ``charged''maintenance''. (1st), on page 28, line 6, "sleeve" was corrected to "sleeve during development." (19), ``Applied'' in the second line from the bottom of page 28 is corrected to ``Applied during development.'' (20), "applied" in the first line from just below No. 29 has been corrected to "applied during development." (21), page 31, line 10, ``After the visible image is repeated'' is corrected to ``After the visible image is formed.'' (22) Of the drawings attached to the application, Figures 6 and 8 are corrected as shown in the attached documents. - Claims 1. In an image forming method in which an image is formed on the image carrier by repeating a step of forming a latent image on the image carrier and a step of developing the latent image using a developer consisting of a plurality of components multiple times. , in each development step, the amplitude of the AC component of the development bias is VAC (v), the frequency is 5 (IIZ),
When the gap between the image carrier and the developer conveying body that conveys the developer is d (mm), 0.2≦VAc/ (d
-f) ((Vac/d)-1soo)/J≦1.0. 2. Claims characterized in that in each development step, the gap between the image carrier and the developer transport member is thicker than the thickness of the developer layer formed on the developer transport member. 3. The image forming method as set forth in claim 1 or 2, wherein the image is characterized by sequentially using the developer having the smallest absolute value of the average charge amount. 4. Any one of claims 1 to 3, wherein the image is characterized by sequentially reducing the amplitude of the AC component of the electric field between the image carrier and the developer transporting member in each developing step. is the image forming method described in item 1. 5. The image forming method according to claim 1, wherein the frequency of the alternating current component of the electric field between the image carrier and the developer transporting member in each developing step is increased in sequence to form an image. The image forming method described in any one of Items 1 to 4. No. 82

Claims (1)

[Scope of Claims] 1. Repeating the steps of forming a latent image on the image carrier and developing the latent image using a developer consisting of a plurality of components several times to form a latent image on the image carrier. In the image forming method for forming an image, in each developing step, the amplitude of the AC component of the developing bias is VA6 (V), the frequency is f (+12),
A developer +! that transports the image carrier and the developer! When the gap between u and the feeding body is d (mm), 0.2≦. /d −
f (i/AC/d) 1500) /f ≦1.0 as 1
An image forming method characterized by 1M1 zuko. 2. For each development, the image bearing member and the JJJ developer transporting member are connected to each other at 1 (formerly 7. The image forming method according to claim 1, characterized in that a multicolor image is formed by sequentially using the image carrier and the image forming agent according to each developer. J.J.
+! An image forming method as set forth in any one of claims 1 to 3, characterized in that a multicolor image is produced by sequentially reducing the amplitude of an alternating current component of an electric field between the toner carrier and the toner carrier. 5. Claims 1 to 4 of the claims, characterized in that a multicolor image is produced by sequentially increasing the frequency of an alternating current component of an electric field between the image carrier and the developer transporting member in each development process. Any of the above is the image forming method described in Section 1.